Pretfit.m from Nectar, humidity, honey bees (Apis mellifera) and varroa in summer: a theoretical thermofluid analysis of the fate of water vapour from honey ripening and its implications on the control of Varroa destructor

This theoretical thermofluid analysis investigates the relationships between honey production rate, nectar concentration and the parameters of entrance size, nest thermal conductance, brood nest humidity and the temperatures needed for nectar to honey conversion. It quantifies and shows that nest humidity is positively related to the amount, and water content of the nectar being desiccated into honey and negatively with respect to nest thermal conductance and entrance size. It is highly likely that honeybees, in temperate climates and in their natural home, with much smaller thermal conductance and entrance, can achieve higher humidities more easily and more frequently than in man-made hives. As a consequence, it is possible that Varroa destructor, a parasite implicated in the spread of pathogenic viruses and colony collapse, which loses fecundity at absolute humidities of 4.3 kPa (approx. 30 gm−3) and above, is impacted by the more frequent occurrence of higher humidities in these low conductance, small entrance nests. This study provides the theoretical basis for new avenues of research into the control of varroa, via the modification of beekeeping practices to help maintain higher hive humidities.

本理论热流体分析研究了蜂蜜产率、花蜜浓度与蜂箱入口尺寸、蜂巢热导率、育幼巢湿度以及花蜜转化为蜂蜜所需温度之间的关联。该分析量化并表明，蜂巢湿度与待脱水转化为蜂蜜的花蜜的总量及含水量呈正相关，而与蜂巢热导率和入口尺寸呈负相关。可以合理推断，在温带气候下的自然蜂巢中，由于热导率与入口尺寸均更小，蜜蜂相较于人工养殖蜂箱，能够更轻松且更频繁地维持更高的蜂巢湿度。据此推测，狄斯瓦螨（Varroa destructor）——一种与致病性病毒传播及蜂群崩溃综合征相关的寄生虫，在绝对湿度达到4.3 kPa（约30 g·m⁻³）及以上时会丧失繁殖能力——会受到这类低热导率、小入口蜂巢中更频繁出现的高湿度环境的影响。本研究为通过优化养蜂实践以维持更高蜂巢湿度、进而实现狄斯瓦螨防控的新型研究方向提供了理论基础。